I've lost count of how many conspiracy theories there are. Among the most daft is "It's in Diego Garcia, the US government has it". As I've said before, I do not believe in the fire or subtle incapacitation of all on board theories either. The reasons for which I have already gone into.

In 99% of most incidents the simplest explanation is often the correct one. That in this case is one of pilot self hijacking for unknown reasons. Suicide seems to be the leading theory and whichever pilot perpetrated it, they were not the first, nor the last to do so.